JEC COMPOSITES MAGAZINE - Issue #77 - December 2012 - 52

tools
About Sandvik Coromant
Sandvik Coromant is the world’s leading supplier of tools, tooling solutions and know-how for the metalworking industry. The company’s customers include major companies in the automotive, aerospace and energy sectors. With a workforce of 8,000, Sandvik Coromant is represented in 130 countries. Sandvik Coromant is part of the business area Sandvik Machining Solutions within the global industrial group Sandvik.

materials with aluminium and/or titanium.

CNC machines
To drill CFRP parts using CNC machine tools, another CD10 PCD-veined drill bit, the CoroDrill® 859V, was developed for unidirectional CFRP materials like M21E, epoxy resins, and bismaleimide (BMI). It has a cutting-edge geometry with two drill tips, minimizing delamination. It also produces good results in CFRPs with coatings like glass fibre or copper. To drill composite CFRP/metal laminates using CNC machine tools, there are CD10 PCD-veined drill bits, e.g. the 86A and 86B series. The 86A series come with a 118° drill tip angle for CFRP/aluminium laminates and the 86B series, a 135° drill tip angle that is better suited for CFRP/titanium laminates. Both series are designed to minimize flash and fibre breaks. Carbon fibre/titanium laminates are some of the hardest materials to machine. Sandvik Coromant and Precorp have been working together to increase the productivity in drilling applications for these materials. To give an idea of the performance of CoroDrill PCD-veined drill bits: a 15-mm-thick CFRP/titanium sandwich with a 10-mm-thick titanium layer can be drilled completely through at a drill speed

of 12 m/min with a feed rate of 0.05 mm/ rev.

One-step drilling
To minimize downtime and achieve high-quality holes with correct tolerances in CFRP and CFRP/metal laminate materials, it is essential to optimize both the PCD-veined drill bit geometries and the application processes. Tools that can complete the drilling operation in a single step are always preferable to reduce production time, but when high precision is required, a second operation, and even a third, can be necessary: pilot hole, drilling, reaming. So far, it has not really been feasible to achieve a reliable and reproducible precision hole-drilling process in a single operation, but that is about to change. The company is performing tests to reduce the cycle time and number of tools needed for drilling operations on aircraft parts. The goal is to achieve one-step drilling in CFRP/aluminium/titanium laminate materials using power-feed machines. The initial results are promising, with hole quality that meets the expectations of major aircraft manufacturers. Thanks to PCD-veined technology, Sandvik Coromant is able to meet the requirements of these manufacturers and to develop specific geometries that are adapted to the different constraints associated with composite materials. But there is more than just drilling; PCDveined tools also exist for contouring and surface grinding. Aircraft tail fins made of composite materials, for example, require difficult contouring operations. PCDveined CoroMill® Plura end mills can be manufactured for this type of operation to minimize fibre tearing and to speed up chip evacuation. PCD-veined technology is undoubtedly the best innovation for performance and cost reduction in composite machining. It contributes a significant competitive advantage, whatever the application. n

amount of time. Even with the latest integrated structures with fewer joints, drilling is still crucial in terms of efficiency and cost. While Sandvik Coromant’s PCD-veined drill bits have cutting-edge geometries designed to minimize delamination at hole entry and exit, the application method is still an important factor in the choice of tool. The CD10 PCD-veined drill bits from the 85 or 85PT series have a diamond-reinforced design that provides more stability for use with a power-feed machine. Parts of the cutting edges are reinforced with PCD to reduce the total length of exposed PCD. In this way, chipping of the edges is prevented and the tool service life increased. These drill bits are also available with cooling from the inside, which is especially recommended for laminated composite

Hole making dominates machining processes in composite materials

More information: www.sandvik.coromant.com/composite

52 jec composites magazine / No77 December 2012

http://www.sandvik.coromant.com/composite

JEC COMPOSITES MAGAZINE - Issue #77 - December 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #77 - December 2012